Environmental Engineering Reference
In-Depth Information
characteristics such as abiotic conditions, land use and part of the biocenosis
(vegetation) that typically occur together. Biotopes are classified into types of
defined, homogenous ecological conditions (Drachenfels
2013
; von Haaren
et al.
2012
). Habitat value points were used to express the effects of measures
for biodiversity. The increase in VPs depend on whether, for example, a mea-
sure is implemented on cropland (value I-II on value scale) or grassland (value
II-V), as well as on site-specific characteristics. Benchmarks and criteria for
valuing each biotope type are given in NLWKN (
2012
) and Drachenfels (
2013
).
The habitat value of the status quo was taken from the landscape master plan,
whereas the value of the target habitat types were referred to the general habitat
values found in NLWKN (
2012
). The upgrading is measured in VP. They were
multiplied by the size of the area covered by the particular biotope types in order
to assess the total effect for the biotope function within a given area. This
procedure was adapted from the assessment of need for compensation measures
found in the German impact mitigation regulation (von Haaren et al.
2012
).
• The landscape master plan identifies areas that are susceptible to soil erosion, as
a result of a model based analysis according to the Universal Soil Loss Equation
(e.g. von Haaren
2004
). Measures have potential effects for soil erosion pre-
vention, when they: (1) extent the period of time when the ground is covered by
vegetation, (2) help shorten the length of steep slopes, (3) lower wind velocity.
Furthermore, effective soil protection in floodplains requires a permanent
ground cover. However, the soil protection effects could not be quantified based
on the given information. They were assessed according to the size of measures
on erosion sensitive sites and to an additional ordinal scaling of the effects (low
(+), medium (++), high (+++)) that considers the time periods of protection
(periodical or permanent effects).
• The reduction of N-input on agricultural land was used as an indicator for
assessing water quality conservation effects of environmental measures. The
accounting refers to the total amount of N-input and is adapted from Osterburg
and Runge (
2007
). Doing so, the assessment of effects on water resource quality
was restricted to nitrogen input in groundwater and surface waters. Possible
inputs of phosphate were not considered in the case study.
• The effects of environmental measures on mitigating Green House Gases were
calculated for CO
2
according to the CO
2
-retention potentials of soil types and
the potential CO
2
-emissions that are caused by agricultural land use as stated in
Saathoff et al. (
2012
). For fens and bogs (groundwater *10 cm under surface),
they calculated a retention potential of 1,700-2,600 t CO
2
/ha. This is assumed to
be the potential reduction of CO
2
-emissions when agricultural land on organic
soils is rewetted and converted into near-natural biotopes. A CO
2
-retention of
70-160 t CO
2
/ha was calculated for hydromophic soils that are used as grassland
([5 years duration), such as Pseudogley, Fluvisols, marsch soils, Gleysole as
well as Pozol.
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